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They are the scourge of British streets and dubbed 'rats with wings' for their unhygienic habits.

But scientists believe an army of urban pigeons could be recruited to help prevent the spread of disease and toxins by acting as constant 'biomonitors.'

The feral birds have an unedifying reputation as pests, but their ability to spread out and occupy all parts of a city could be harnessed to keep track of toxins and diseases which damage human health, say experts.

Rebecca Calisi-Rodriguez, of the University of California, believes pigeons are a perfect tool for monitoring dangerous pollutants because they live off human waste and are therefore inhabit same areas as city dwellers and are exposed to the same contaminants.

The California team said pigeons could serve as 'the proverbial canary in the coal mine' because they 'walk on the same pavements, breathe the same air and eat the same food as humans.'

"Pigeons have existed for ages in close proximity to us, eating the same food, drinking and being exposed to the same water sources, soil, air, pollution," said said Dr Calisi-Rodriguez, associate professor of neurobiology, physiology and behaviour.

"They have a very small home range, spending the their life within a few neighborhood blocks. And because they are alive they process these chemicals in their bodies.

"This offers up the opportunity to not only find toxin hot spots in our environment, but to understand HOW these toxins affect biology."

There are 18 million feral pigeons in Britain so scientists would have a huge supply of birds which could act as biomonitors. Credit:
David Slipher/UC Davis

There are 18 million feral pigeons in Britain so scientists would have a huge supply of birds which could act as biomonitors.

In a recent study, the team set out to find out if pigeons could highlight areas which were high in lead pollution.

Although lead has been banned from products for decades - because it harms brain development - it is still present in the many cities, often in old painted street furniture, or children's play equipment.

Ass Prof Calisi-Rodriguez' studied the blood levels of pigeons and children living in New York between 2010 and 2015 and found that both birds and humans inhabiting the same neighborhoods experienced similar patterns of lead in their blood.

The team has also received funding to start screening pigeons for other toxins including, pesticides, fire retardants, BPA, and other heavy metals. They are even monitoring the genetic make-up of the birds to see how stress affects DNA.

"Birds, like us, are vertebrates," added Ass Prof Calisi-Rodriguez. "We share a lot of the same evolutionary history, and our bodies have many similarities in terms of tissue form and function.

"For example, like humans, pigeons lactate. They produce crop milk in their crop sacs to feed their chicks when they first hatch.

"The process is controlled by the same hormones that control human milk production, and both types of milk have essential nutrients the babies need to survive. So as you see, what we learn in birds can have far-reaching implications."